JPH1098713A - Video signal switch device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video signal switch device which can switch a video signal encoded into an MPEG system adequately in a picture unit by suppressing deterioration in picture quality to a minimum period and a minimum extent. SOLUTION: Sources 1 and 2 from a 1st switcher 10 are converted by 1st and 2nd decoders 11 and 12 into base-band video signals, which are delayed by one GOP period through 1st and 2nd delay circuits 13 and 14 respectively. A 2nd switcher 15 switches a video signal from the source 1 o the source 2 in a frame where a control part 19 instructs switching and the signal is reencoded by an encoder 16 and timed by a 3rd delay circuit 17. A 3rd switcher 18 selects the delayed source 1 from the 1st delay circuit 13 first, selects the output of the 3rd delay circuit 17 right before the 1st I picture after switching signal input, and then selects the source 2 being the output of the 2nd delay circuit 14 prescrived GOPS's later.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal switching apparatus which can be applied to various video signal processing systems and which can appropriately switch a plurality of video signals encoded by the MPEG system.

[0002]

2. Description of the Related Art With the development of image processing technology and signal processing technology, various systems for compressing and encoding video (moving image) signals have been proposed and are being put to practical use. One of the various video coding methods that can perform high-quality and high-efficiency coding, and the widely used method is MP
There is an EG method (a high-quality moving image coding method by the Moving Picture coding Experts Group). In MPEG,
The input screen is a picture type (I (Intra coded) picture, P (Predictive coded) picture, B (Bidirectio
nally predictive coded (picture), and perform motion compensation prediction and DCT coding. Then, the obtained DCT coding coefficient is quantized, variable-length coded together with a motion vector and coding mode information, and output as an MPEG stream. At this time, in the case of I and P pictures, the quantized information is subjected to inverse quantization, inverse DCT and motion compensation and locally decoded, and the same image as that of the decoder is restored and stored in the frame memory. Used as a reference screen for compensation prediction. Recording and transmission of an encoded video signal using such a video encoding technique has been actively performed.

[0003]

However, the aforementioned MP
The EG method is used between pictures (between frames and between fields).
Since the encoding is performed using the correlation of a plurality of video signals, that is, a plurality of video signals, that is, MPEG
There is a problem that the stream cannot be switched using an arbitrary picture as a switching position. More specifically, if the MPEG stream is switched on a picture basis, it will not be possible to decode appropriately near the switching position, and the image quality of that portion will be significantly degraded. This deterioration in image quality continues until the next I picture in the MPEG stream is decoded, and a normal video signal can be obtained by decoding the I picture.

[0004] Therefore, if it is necessary to perform switching at an arbitrary point in the past, the coded video signal is decoded once, and the switching is performed using the decoded video signal. The signal was re-encoded. However, in such a method,
Coding is repeated for all video signals, which causes a problem that image quality is deteriorated for all video signals.
In particular, there was a great effect on video signals of low bit rate. Further, in order to perform such processing using an encoded video signal, a method in which all pictures are encoded as I pictures, that is, an encoding method using no correlation between pictures can be considered. However, such a method has a problem that the coding efficiency is extremely deteriorated, and is not a practical method.

Accordingly, an object of the present invention is to provide a video signal switching device capable of minimizing the deterioration of the image quality for a minimum period and to a minimum, and capable of appropriately switching a video signal encoded by the MPEG system on a picture basis. It is in.

[0006]

In order to solve the above-mentioned problems, decoding is performed in units of GOP only at switching points, switching is performed in units of pictures using the decoded video signals, and encoding is performed again. The GOP at the switching point is arranged in a new MPEG stream so as to match the signal of another part used as encoded.

Therefore, the video signal switching device of the present invention
A first MPEG stream that is currently output, two decoding units that respectively switch and decode a second MPEG stream that is output next, and any one of the decoded first and second video signals Selecting means for switching the signal from the first video signal to the second video signal at a desired position, and switching the generated video signal to the same MPG as the original MPEG stream.
Re-encoding means for re-encoding by the EG encoding method, and usually selecting the first MPEG stream, selecting the re-encoded MPEG stream at the switching position, and then selecting the second MPEG stream Output switching means for switching from the first MPEG stream to the second MPEG stream.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a video signal switching device according to the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a block diagram illustrating a configuration of a video signal switching device according to the present embodiment. The video signal switching device 1 includes a first switcher 1
0, a first decoder 11, a second decoder 12, a first delay circuit 13, a second delay circuit 14, a second switcher 15, an encoder 16, a third delay circuit 17, a third switcher 18, control unit 19, operation unit 20, a display unit 21 and the monitor 22 _-1 to 22 _-3.

First, the configuration and function of each unit will be described. The first switcher 10 is a matrix switcher having a plurality of input channels to which a plurality of MPEG streams are input in parallel and two output channels, and based on a switching instruction signal from the control unit 19, an arbitrary input channel. To any output channel. That is,
The first switcher 10 connects one of an input channel and an output channel to which an MPEG stream to be output from the video signal switching device 1 is input at present or immediately, and the MPEG stream is appropriately output to a subsequent component. To do. Also, while the MPEG stream is being output from the video signal switching device 1, an input channel to which the next MPEG stream to be switched and output is input is connected to the other of the output channels, and the MPEG stream is output. Is also appropriately output to the subsequent components. Note that the switching instruction from the control unit 19 may be an instruction to switch immediately, or an instruction to switch at a specified time. Switching in the first switcher 10 is performed in synchronization with a reference signal Ref input from the outside.

[0010] The first decoder 11 and the second decoder 12 decode the MPEG streams selected and input by the first switcher 10 as baseband video signals, respectively. At this time, information indicating what picture type each frame of the decoded video signal was at the time of the original coded signal (whether it is an I picture, a P picture, or a B picture) is also output. This decoding is also performed in synchronization with the externally input reference signal Ref.

A first delay circuit 13 and a second delay circuit 14 re-encode two MPEG streams selected and input by the first switcher 10 by an encoder 16 in a third switcher 18 at the subsequent stage. M
The timing is adjusted by delaying by the frame time unit so that the consistency as a moving image sequence can be obtained even when switching to the PEG stream. This delay operation is also performed in synchronization with the externally input reference signal Ref.
The second switcher 15 switches baseband video signals output from the first decoder 11 and the second decoder 12 based on an instruction signal from the control unit 19. The switching instruction from the control unit 19 includes a case where an immediate switching is instructed and a case where a switching is instructed by specifying time. Further, switching in the second switcher 15 also includes:
This is performed in synchronization with the reference signal Ref.

The encoder 16 includes a second switcher 15
Baseband video signal output from
Re-encode. In the MPEG re-encoding, the information of the picture type output from the first decoder 11 and the second decoder 12 is used to encode each encoded signal so as to be the same as the picture type. Also, the encoder 16
Is encoded in a closed GOP if there is no instruction from the control unit 19, and the designated G
Encoding is performed as a normal GOP (open GOP) after a closed GOP by the number of OPs. This encoding is also performed in synchronization with the externally input reference signal Ref. The third delay circuit 17 delays the output of the encoder 16 in units of frame time so that the third switcher 18 can switch the MPEG stream at the beginning of the GOP even if switching is performed in the last frame of the GOP. . This process is also performed in synchronization with a reference signal Ref input from the outside.

The third switcher 18 performs switching of the MPEG stream in synchronization with the external reference signal Ref based on an instruction from the control unit 19, and generates an switched MPEG stream in desired picture units. Output. Specifically, in the third switcher 18, when switching from the video signal of the source 1 to the video signal of the source 2, the first delay circuit 13 and the The switching is performed in the order of the third delay circuit 17 and the second delay circuit 14, and when switching from the video signal of the source 2 to the video signal of the source 1, the second delay circuit 14, the third delay circuit 17, Switching is performed in the order of one delay circuit 13.

The control unit 19 controls the video signal switching device 1 based on an instruction from the operation unit 20 or a host computer (not shown) so that the video signal switching device 1 performs a desired operation.
Control each part of In addition, the control unit 19 displays necessary information on the display unit 21 in accordance with the control, and appropriately transmits a state to the host computer.

The operation of the control unit 19 will be described with reference to FIG. FIG. 2 is a flowchart illustrating the operation of the control unit 19. First, when the operation of the video signal switching device 1 is substantially started (Step S1), after initializing each part of the video signal switching device 1 (Step S1).
2) Perform initial setting of the first to third switchers 10, 15, and 18 (step S3). That is, first, in the first switcher 10, the input channel to which the MPEG stream to be output first is input is set to the MPE of the source 1.
The input channel and the output channel are switched so as to output to the first decoder 11 and the first delay circuit 13 as a G stream. In the third switcher 18, the source 1 is simply delayed by the first channel. The output is switched so that the output of the delay circuit 13 is selected and output.
In the second switcher 15, switching is performed so as to select a baseband video signal as a result of decoding the MPEG stream of the source 1 by the first decoder 11 for the time being.

After such initial settings, the operation unit 2
The process proceeds to a normal process that operates based on an instruction from the host computer 0 or an upper-level computer (not shown) (hereinafter, also referred to as an external computer). First, it is checked whether an end instruction has been input from the outside (step S4). Here, when the end instruction has been input, end processing is performed on each unit of the video signal switching device 1 (step S5), and the processing ends (step S6).

If no end instruction has been input in step S4, it is next checked whether or not an instruction has been input from the outside to select an input MPEG stream, that is, an MPEG stream to be switched next (step S7). ). If the instruction to select the input MPEG stream has been input, the first switcher 10 switches the input channel to which the next MPEG stream to be output after switching from the currently output MPEG stream to the current MPEG stream. Is output as a source output different from the source output from which
Switching between input and output channels (step S
8). For example, in the case immediately after the initial setting described above, the second decoder 12 and the second decoder 12 are used as the source 2 MPEG streams so that the next MPEG stream can be switched to the MPEG stream currently output as the source 1 and output. The input channel and the output channel are switched so as to output to the delay circuit 14 of FIG. This next MP
When the selection of the EG stream is completed, step S4 is performed again.
Return to and wait for the next instruction.

In step S7, if there is no input selection instruction, it is checked whether an instruction to switch the MPEG stream has been input (step S7).
9). If the switching instruction has been input, it is checked whether to switch from source 1 to source 2 or from source 2 to source 1 based on the current state (step S10).

When the switching of the MPEG stream from the source 1 to the source 2 is instructed, first, the second
The signal selected by the switcher 15 of the first decoder 1
The video signal of the source 1, which is the output of the first decoder 12, is switched to the video signal of the source 2, which is the output of the second decoder 12 (step S11). Next, the signal to be selected by the third switcher 18 is changed from the MPEG stream of the source 1 output from the first delay circuit 13 to the third delay circuit 17 at the transition point from the latest B picture to the I picture. (Step S1)
2). Then, MPEG for a predetermined number of GOPs is determined.
After waiting for the stream to be output from the third delay circuit 17 (step S13), the signal selected by the third switcher 18 is further switched to the source 2 MPEG stream output from the second delay circuit 14. (Step S14). Thus, the switching from the source 1 MPEG stream to the source 2 MPEG stream is completed, and the process returns to step S4 to follow an external instruction.

In step S10, if the switching of the MPEG stream from the source 2 to the source 1 has been instructed, first, the signal selected by the second switcher 15 is output to the source which is the output of the second decoder 12, 2 from the video signal of the first decoder 11
(Step S15). Next, the signal selected by the third switcher 18 is converted from the MPEG stream of the source 2 output from the second delay circuit 14 to the third point at the transition point from the latest B picture to the I picture.
Is switched to the MPEG stream output from the delay circuit 17 (step S16). Then, MPEG streams for a predetermined number of GOPs are supplied to the third delay circuit 1.
7 is output (step S17).
Is switched to the source 1 MPEG stream output from the first delay circuit 13 (step S18). Thus, the switching from the source 2 MPEG stream to the source 1 MPEG stream is completed, and the process returns to step S4 to follow the external instruction. The control unit 19 performs such an operation.

The operation unit 20 is an input device for instructing switching of the first switcher 10 and switching of the second switcher 15. The display unit 21 is a display device for displaying the operation status of the video signal switching device 1. The monitors 22 _{-1 to} 22 _-3 each include a first decoder 1
1, the baseband video signal of source 1 decoded by 1,
This is a monitor for confirming the baseband video signal of the source 2 decoded by the second decoder 12 and the baseband video signal resulting from switching by the second switcher 15.

Next, the operation of the video signal switching device 1 will be described with reference to specific examples of FIGS. Regarding the operation of the video signal switching device 1, the third switcher 18 selects the MPEG stream in which only one GOP including the switching position of the video signal is re-encoded, and the re-encoding of a plurality of GOPs including the GOP. The case where the selected MPEG stream is selected will be described. In addition, FIG.
In FIG. 6, Xi and Yi are frame signals of the video signals X and Y, respectively, and the subscript i is a frame number. This frame number matches the time series in the baseband signal. Xi and Yi indicate that the video signal has been decoded once and returned to the baseband video signal. Also, I, P, and B respectively indicate the picture type at the time of encoding the frame, and ○ added to the I picture indicates that the GOP starting from the I picture is a closed GOP.

First, the operation of the video signal switching apparatus 1 when decoding and re-encoding only one GOP including a switching portion when switching the MPEG stream will be described with reference to FIGS. FIGS. 3A and 3B are diagrams showing signals in each part of the video signal switching device 1 in such a case, wherein FIG. 3A is a diagram showing the original MPEG stream X, and FIG. 3B is a diagram showing the MPEG stream X decoded by the decoder. FIG. 7 is a diagram showing a video signal X (dec) obtained by the following method.
(C) is a diagram showing an MPEG stream X (delay) obtained by delaying the MPEG stream X in the delay circuit,
(D) is a diagram showing the next MPEG stream Y to be switched, (E) is a diagram showing a video signal Y (dec) obtained by decoding the MPEG stream Y in the decoder, and (F) is a diagram showing the MPEG stream Y. FIG. 3 is a diagram showing an MPEG stream Y (delay) delayed by a delay circuit, (G) is a diagram showing a baseband video signal X + Y (base) to be switched, and (H) is a video signal X + Y.
FIG. 4 is a diagram showing an MPEG stream X + Y (enc) obtained by re-encoding (base) in an encoder, and (I) shows the MP stream thereof;
FIG. 7 is a diagram showing MPEG streams X + Y (delay) obtained by delaying an EG stream X + Y (enc) in a delay circuit. FIG. 6 (J) shows MPEG streams X + Y (sw) which are appropriately selected and output by a third switcher 18. FIG. Note that the numbers in FIG. 3A indicate time.

First, two MPEG streams X and Y to be switched are shown in FIGS. 3A and 3D. As shown in the figure, these are a cycle M = 3 in which an I or P picture appears, the number of pictures N = 6 in a GOP,
Further, the MPEG stream has the same I-picture phase. In the first switcher 10, MPEG
Stream X is a source 1 and an MPEG stream Y
Is output as source 2. Then, the MPEG stream X is decoded by the first decoder 11, and
A baseband video signal X (dec) as shown in FIG. Also, the MP input to the first delay circuit 13
The EG stream is delayed just one GOP period,
(C) A delayed MPEG stream X (d
elay) is generated.

Next MPEG stream Y to be switched
Similarly, the baseband video signal Y (dec) as shown in FIG. 3E is generated by decoding by the second decoder 12, and is delayed by the second delay circuit
An MPEG stream Y (delay) as shown in (F) is generated. Then, in the second switcher 15,
Initially selects the output of the first decoder 11 corresponding to the source 1, when the operator instructs the change of the image from the operation unit 20, such as by monitoring the monitor 22 _-1 to 22 _-3, the instruction The video signal to be selected is switched to the video signal of the source 2 output from the second decoder 12 based on the switching signal generated by the control unit 19 according to (1). For example, as shown in FIG. 3, if this switching is performed before time 7, that is, immediately before the X6 frame, the second switcher 15 outputs a frame Y6 next to the frame X5 as shown in FIG. Is generated and output.

The GOP including the Y6 frame is re-encoded by the encoder 16 while maintaining the previous picture type, to generate an MPEG stream for one GOP as shown in FIG. The delay circuit 17 delays by NM frames, that is, three frames in the example of FIG.
And the same time series and the same phase as the MPEG streams X (delay) and Y (delay) delayed by the second delay circuit 14.
An EG stream X + Y (delay) is generated. And
The third switcher 18 first selects the MPEG stream X (delay) shown in FIG. 3C, which is the output of the first delay circuit 13, and selects the first I picture after the switching signal is input. The MPE shown in FIG. 3I which is the output of the third delay circuit 17 before the time, that is, before the time 12.
G stream X + Y (delay) is selected, and after one GOP has elapsed, that is, before time 18, the MPEG stream Y (del) shown in FIG.
ay) is selected to generate and output an MPEG stream X + Y (sw) as shown in FIG.

As described above, in the video signal switching device 1, only the frames of Y8, Y6, Y7, Y11, Y9, and Y10 at times 12 to 17 are decoded and re-encoded.
The portion where the image quality deteriorates to some extent can be reduced in a short time. In addition, since the re-encoding is performed so that those picture types are the same as the original picture types, the degree of image quality deterioration of the portions is reduced.

FIG. 4 is a diagram showing the relationship between the switching position and the output of the second switcher 15 and the output of the encoder 16 when switching over such an MPEG stream. FIG. 9B shows each output when switching is performed immediately before the first frame of the GOP (time 7, immediately before frame Y6), and FIG. 11B shows the output immediately before the second frame (time 8, immediately before frame Y7). FIG. 4C is a diagram showing each output when switching is performed, FIG. 4C is a diagram showing each output when switching is performed immediately before the third frame (time 9, immediately before frame Y8), and FIG. FIG. 11E shows the outputs when the switching is performed immediately before the fourth frame (time 10, immediately before frame Y9). FIG. 10E shows the switching immediately before the fifth frame (time 11, immediately before frame Y10). Is done Illustrates each output, (F) is the 6 th frame immediately before (time 12, the previous frame Y11)
FIG. 7 is a diagram showing each output when switching is performed in FIG.

As shown in FIG. 4, M
Even if the switching of the PEG stream is instructed, the time of the switching instruction is set to the GO including the switching position.
The first I-picture frame of P is the third switcher 1
8 (time 1 in the example of FIGS. 3 and 4).
2) As before, the output of the third delay circuit 17 can be selected for that GOP, and switching can be appropriately performed for all switching positions.

Next, the operation of the video signal switching apparatus 1 when decoding and re-encoding a plurality of GOPs after the GOP including the switching portion when switching the MPEG stream will be described with reference to FIGS. Will be explained. FIG. 5 is a diagram showing signals in each section of the video signal switching device 1 in such a case, and (A) to (J) are the same as those in FIG. 3 described above. Also in this case, two MPEGs as shown in FIGS. 5A and 5D are used.
Streams X and Y are input as source 1 and source 2, respectively. And the MPEG stream X is the first
5B is generated by the decoder 11 shown in FIG. 5B, and the baseband video signal X (dec) as shown in FIG. 5B is generated. Such a delayed MPEG stream X (delay) is generated. The MPEG stream Y is decoded by the second decoder 12 and
A baseband video signal Y (dec) as shown in FIG. 8E is generated, and the second delay circuit 14 just outputs one GOP.
A delayed MPEG stream Y (delay) is generated as shown in FIG.

In the second switcher 15, a video signal to be selected is output from the first decoder 11 based on a switching signal generated by the control unit 19 based on an operator's switching instruction. Second from signal
Is switched to the source 2 video signal output from the decoder 12. For example, as shown in FIG. 5, if this switching is performed just before time 7, that is, immediately before the X6 frame, the second switcher 15 outputs the frame Y6 next to the frame X5 as shown in FIG. Is generated and output.

The encoder 16 re-encodes two GOPs from the GOP including the Y6 frame while maintaining the previous picture type. At this time, the first GOP is regarded as a closed GOP and the second GO
P is coded as an open GOP. As a result, an MPEG stream for 2 GOPs as shown in FIG. 5I is generated, and further delayed by NM frames, that is, 3 frames in the third delay circuit 17, so that the first delay circuit 13 MPEG streams X + Y (delay) having the same time series and the same phase as the MPEG streams X (delay) and Y (delay) delayed by the second delay circuit 14
Is generated. Then, in the third switcher 18, the output of the first delay circuit 13 is initially shown in FIG.
5 (I), which is the output of the third delay circuit 17 before the first I picture after the switching signal is input, that is, before time 12, after the MPEG stream X (delay) shown in FIG. The MPEG stream X + Y (delay) is selected, and after the lapse of 2 GOPs, that is, before the time 24, the output of the second delay circuit 14 shown in FIG.
The PEG stream Y (delay) is selected, and an MPEG stream X + Y (sw) as shown in FIG. 5 (J) is generated and output.

As described above, by performing re-encoding on a plurality of GOPs, the re-encoded G
It is possible to gradually reduce image quality deterioration due to a difference in reference image when moving from the OP to the GOP of the original MPEG stream, and it is possible to generate an MPEG stream with a smaller degree of image quality deterioration. For example, in the example of FIG. 5, Y1
7 (P picture) and Y17 (P picture) can be reduced, and the deterioration of the image quality of Y18 (B picture) and Y19 (B picture) at the time of decoding can be reduced.

FIG. 6 shows such an MPEG as in FIG.
A switching position when switching to a stream, an output of the second switcher 15, and an encoder 16
7A to 7F are diagrams illustrating the relationship between outputs of the multiplexing.
It is a figure which shows each output when switching is performed immediately before the 1st to 6th frames in OP. As shown in FIG. 6, no matter where in the GOP the switching of the MPEG stream is instructed, the time of the switching instruction is
Since the frame of the first I picture of the GOP including the switching position is input to the third switcher 18 (time 12 in the examples of FIGS. 5 and 6), the third I / O frame is set to the third position. The output of the delay circuit 17 can be selected, and switching can be appropriately performed for all switching positions.

As described above, in the video signal switching apparatus 1 according to the present embodiment, the switching of the MPEG stream can be performed in frame units in real time. Further, the image quality is slightly deteriorated only in the vicinity of the switching position, but otherwise, the original MPEG stream is used, so that the image quality is not deteriorated at all.

The present invention is not limited to the embodiment, and various modifications are possible. For example, the configuration of the video signal switching device 1 is not limited to that shown in FIG. 1 and may be suitably modified. Further, the MPEG stream exemplified in the present embodiment has a configuration in which the period M in which an I or P picture appears is M = 3DE, and the number of pictures in a GOP is N = 6. However, the present invention is not limited to this.
It can correspond to the P configuration. Further, in the encoder 16, only the video signal finally selected by the third switcher 18 may be re-encoded, or only a part of the video signal which may be selected may be re-encoded, Re-encoding may be always performed irrespective of the presence or absence of switching, and the operating conditions and the like may be arbitrary.

[0037]

As described above, according to the video signal switching apparatus of the present invention, the degradation of the image quality is minimized for the first period and the video signal coded by the MPEG system is appropriately switched on a picture basis. can do.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video signal switching device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining an operation of a control unit of the video signal switching device shown in FIG.

FIG. 3 shows a video signal switching device shown in FIG.
It is a figure for explaining operation at the time of decoding and re-encoding only OP, (A) is a figure showing original MPEG stream X, (B) is a decoded baseband video signal X ( dec), (C) is a diagram showing a delayed MPEG stream X (delay),
(D) is a diagram showing a next MPEG stream Y to be switched, (E) is a diagram showing a decoded baseband video signal Y (dec), and (F) is a diagram showing a delayed MPEG stream.
FIG. 3 is a diagram showing a stream Y (delay), FIG. 3 (G) is a diagram showing a switched baseband video signal X + Y (base), and FIG. 3 (H) is a diagram showing a re-encoded MPEG stream X +
FIG. 5 is a diagram showing Y (enc), wherein (I) shows a further delayed M
FIG. 3 is a diagram showing a PEG stream X + Y (delay);
(J) is a diagram showing an output MPEG stream X + Y (sw).

FIG. 4 shows a 1G video signal switching device shown in FIG.
FIG. 10 is a diagram illustrating a relationship between a position of a switching instruction for an MPEG stream, an output of a second switcher, and an output of an encoder in an operation when decoding and re-encoding only an OP, and (A) to (F). FIG. 8 is a diagram illustrating an output of a second switcher and an output of an encoder when switching is performed immediately before the first to sixth frames in a GOP.

5A and 5B are diagrams illustrating an operation when decoding and re-encoding a plurality of GOPs in the video signal switching device illustrated in FIG. 1, wherein FIG. 5A illustrates an original MPEG stream X; (B) is a diagram showing a decoded baseband video signal X (dec), (C) is a diagram showing a delayed MPEG stream X (delay),
(D) is a diagram showing a next MPEG stream Y to be switched, (E) is a diagram showing a decoded baseband video signal Y (dec), and (F) is a diagram showing a delayed MPEG stream.
FIG. 3 is a diagram showing a stream Y (delay), FIG. 3 (G) is a diagram showing a switched baseband video signal X + Y (base), and FIG. 3 (H) is a diagram showing a re-encoded MPEG stream X +
FIG. 5 is a diagram showing Y (enc), wherein (I) shows a further delayed M
FIG. 3 is a diagram showing a PEG stream X + Y (delay);
(J) is a diagram showing an output MPEG stream X + Y (sw).

FIG. 6 is a diagram illustrating an example of an operation of decoding and re-encoding a plurality of GOPs in the video signal switching device illustrated in FIG. It is a figure which shows the relationship of an output, (A)-(F) respectively shows the output of the 2nd switcher and the output of an encoder when switching is performed immediately before the 1st-6th frame in a GOP. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Video signal switching device, 10 ... 1st switcher, 11
... first decoder, 12 ... second decoder, 13 ... first
, A second delay circuit, a second switcher, a 16 encoder, a third delay circuit,
8: third switcher, 19: control unit, 20: operation unit,
21: display unit, 22: monitor.

Claims (8)

[Claims] 1. A video signal switching device for switching a plurality of input MPEG streams and outputting them as one MPEG stream, comprising: a first MPEG stream input and output; and a first MPEG stream input and output. Two decoding means for switching from the MPEG stream to output the next MPEG stream, respectively, to generate a first video signal and a second video signal; and Means for selecting one of a video signal and a second video signal, usually selecting the first video signal, and selecting the second video signal from the first video signal at an input switching position And selecting means for selecting a second video signal thereafter, and converting the selected video signal to the first MPEG stream and the second MPEG stream. Same MPE
Re-encoding means for re-encoding by the G-encoding method to generate an MPEG stream; and re-encoding of the input first MPEG stream, the input second MPEG stream, and the re-encoded MPEG stream. Means for selecting any one of the first and second MPEG streams, normally selecting the re-encoded MPEG stream for a predetermined period near the switching position, and after the predetermined period A video signal switching device comprising output selection means for selecting and outputting each of the second MPEG streams. 2. The apparatus according to claim 1, wherein the output selection means is configured to output the re-encoded MPEG data for a period of one GOP including the switching position.
Select a stream, and after said GOP, said second MPE
The video signal switching device according to claim 1, wherein the G stream is selected. 3. The re-encoding means according to claim 1, wherein said re-encoding means comprises a GOP in a first MPEG stream and a second MPEG stream.
3. The video signal switching device according to claim 2, wherein a GOP including the switching position of the selected video signal corresponding to a configuration is set as a closed GOP, the phases of the I pictures are made the same, and re-encoding is performed using the same MPEG encoding method. . 4. The output selecting means selects the re-encoded MPEG stream for a plurality of predetermined GOPs after the GOP including the switching position, and after the plurality of GOPs, outputs the second MPEG stream. Claim 1 to select
The video signal switching device according to the above. 5. The apparatus according to claim 1, wherein said re-encoding means includes a GOP in the first MPEG stream and a second MPEG stream.
A GOP including the switching position of the selected video signal corresponding to the configuration is set as a closed GOP, and G
5. The video signal switching device according to claim 4, wherein each OP is an open GOP, the phases of I-pictures are the same, and re-encoding is performed using the same MPEG encoding method. 6. The phase of the input first MPEG stream, the input second MPEG stream, and the phase of the MPEG stream re-encoded by the re-encoding means, which are input to the output selection means. Further comprising timing adjustment means for adjusting the input timing of each stream to the output selection means, so that
Said output selecting means, wherein said first MPEG stream whose phase has been adjusted to be the same by said timing adjusting means,
6. The video signal switching device according to claim 5, wherein one of the second MPEG stream and the re-encoded MPEG stream is selected. 7. A switching instruction means for instructing a switching position from the first MPEG stream to the second MPEG stream, wherein the selecting means is configured to switch the first image at the designated switching position. Switching from the signal to the second video signal, the output selecting means, when a switching position is designated by the switching instruction means, for a predetermined number of GOPs after the GOP including the designated switching position 7. The video signal switching device according to claim 6, wherein the re-encoded MPEG stream is selected. 8. An input selection for selecting the first MPEG stream selected and output from a plurality of MPEG streams, and selecting the second MPEG stream to be switched to the first MPEG stream and output next. Means for selecting, as the first MPEG stream, an MPEG stream which has been switched and output has been started after the switching of the video signal has been completed, and the original MPEG stream which has been switched and output has been completed. A new MPEG stream is replaced by the second MP stream instead of the first MPEG stream.
Multiple MPs by selecting as EG stream
The video signal switching device according to claim 7, wherein the video signal switching device sequentially switches the EG streams.